by Wayne Myers
Price Each: $449.00 retail, $169.99 street.
Several months ago I undertook the construction of a pair of LXmini speakers from kit. The design, by Sigfried Linkwitz of Linkwitz Lab, had made a splash at audio shows and I had been impressed by their capability as a small and economical reference speaker. With the sponsorship of Linkwitz Lab (plans), Madisound (kit), and miniDSP (DSP), the LXmini pair was completed.
The sound is everything I remembered, but I was soon seeking a solution to the design's shortcomings - you can not play them very loud, and bass below 50 Hz is almost non-existent. Linkwitz/Madisound have provided a solution in the form of a dipole woofer design/kit, with a pair running in the neighborhood of $1,000. Out of curiosity, I have been on the lookout for a finished commercial subwoofer that would meet the following criteria:
- Economical, under $200 each so a pair could be purchased and run in stereo mode with the LXmini (see reasons below).
- Response beyond 150 Hz at the top end, so a crossover with the LXmini could take over the lowest octave or two and allow them to be driven louder with low distortion, and down to 30 Hz or below to give solid 2-channel bass support and reasonable - although not bone-crushing - home-cinema support.
- A 10-inch or larger driver, for more air movement with less excursion range and lower distortion, along with the desired low-frequency capability. This is a design parameter, of course, that a good subwoofer design will make use of appropriately. There are some very good subs out there with smaller drivers. But high output, low distortion, and low frequencies all together tend to call for larger drivers, so it was a bullet point that I was a bit stuck on.
- Amplification capable of 200 W rms and 400 W peak, or in that range.
- A trustworthy brand with good customer support.
One day recently I happened upon the JBL ES150P, which seemed to satisfy all the wants on my list, so I ordered up a pair.
Delivery and Unboxing
The pair I ordered arrived 2 days later, via standard free Amazon Prime shipping, and transported by my friendly US Mail delivery person. Each carton weighed only 45 pounds, so hefting them around was not a problem, even having a back that demands a bit of TLC when it comes to lifting. Inside the standard-weight carton, top and bottom foam spacers mounted on additional cardboard give minimally-adequate spacing and protection. The ES150P is then inside a cloth cover which is inside a plastic cover, so finish is well protected. The speaker itself weighs in at 39 pounds, with a footprint that is fairly easy to place - I would have been surprised to find a sub with the ES150P capability in a much smaller enclosure.
The color model I received is the P150PBK, with black sides and a brushed gray top and front (behind the grille). Cherry and Beech are options - this applies only to the left and right decorative side panels. On top of the unit is a power/status LED that is red when power is applied but in standby mode, and green when program material is detected. The rear panel contains the power connector and switch, dual RCA input connectors, Crossover frequency adjustment (24 dB/octave, continuously variable from 50 Hz to 150 Hz), Level, input type selection (LFE or Line), and Phase switch. The LFE input setting bypasses the crossover circuit completely, for use with Bass Management elsewhere in the system.
The grille is black, mounting via four posts that mate with mounting holes on the front of the enclosure. The patented 10-inch PolyPlas driver, with HeatScape motor structure, is made to play long and hard, while staying cool and keeping distortion low. Driven by an amplifier with 300 W rms and 500 W peak power capability, the ES150P seemed to promise potent volume levels. Little detail is given about the amplifier in JBL's documentation, although JBL is the kind of company that is not bashful about defining precisely how they measure the amp's peak power output capability. The LF spec for the ES150P is 28 Hz, so my desire to reach down to 30 Hz was met. And the enclosure is magnetically shielded, typical for a unit that might be used as part of a PC audio setup.
I wanted a front-mounted driver for best hope of integration with the LXmini, and the ES150P provides that, along with a bottom-mounted port for enclosure tuning.
The large rubber feet were a bit of a mystery. The tip of each comes off, suggesting there is more there than meets the eye, but there is nothing more to be done with it, no hidden spikes, and no mention of it in the manual.
JBL boasts free shipping and returns when purchasing direct, along with free lifetime support.
Specifications and Measurements
The first unit went straight to the back patio for measurements. I was pleased to find smooth response clear up to 200 Hz, but was a little concerned about the low end, which rolled off quickly below 40 Hz. I hoped in-room performance at the low-frequency end would be better.
Review Test Equipment
Setup and First Impressions
Subwoofer setup is a science that could fill volumes, but my application defies many of the rules that would be found therein. Subwoofers in a typical audio setup run only at 80 Hz and below, and will be placed in the listening room for optimum frequency response over some limited listening area. In my setup, the ES150B would be running with frequencies up to 150 to 200 Hz range, well above the point where localization becomes an issue (normally considered 80 Hz). So the two subs had to be placed close to the LXmini speakers for soundstage and imaging (SS&I) integration. Frequency response integration would also need to be as smooth as possible at crossover.
Initial in-room measurements were disappointing, although not surprising. The smooth response at the desired crossover point in outdoor measurements was replaced by multiple room modes. The desired crossover frequency had been moved to 200 Hz once I saw what the ES150B outdoor measurements indicated. But the room modes between 100 Hz and 200 Hz had to be delt with.
Quick early listening tests indicated that the ES150B could reach low and put out lots of clean volume. But the messy response between 100 and 200 Hz was going to need attention.
It is not uncommon to work with delay settings to attempt to vary phase relationships at crossover and/or at other critical room mode frequencies. The goal is to get multiple subs working as one, providing smooth frequency response. This works well with subs operating below 80 Hz, but with frequencies up to 200 Hz expected, the game changes completely. Using the miniDSP 4x10 for crossover, it became apparent that a +/- 1 mS delay change could be tolerated, and that amount of delay variation made almost no difference in the room modes targeted. At +/- 2 mS delay change the SS&I was beginning to be impacted, and at +/- 3 mS delay change, the SS&I shift became intolerable, while almost no noticeable improvement had been made in the room modes or in smooth transition at crossover. Delay variations were quickly abandoned.
Crossover settings with the miniDSP 4x10 are infinitely variable. What fun! And what a great way to create an audio disaster! To make a long story short, an LXmini/sub crossover above 180 Hz causes serious SS&I degradation, while crossover below 150 Hz with steep crossover slopes is safe. I played with slopes and cutoff frequencies to find a combination, along with phase shift changes, that improved the room modes markedly and almost eliminated the awful multi-node notch just above 100 Hz, but SS&I changes were very noticeable and for the worse! I finally ended up with the sub low-pass set at LR48 (Linkwitz-Riley, 48 dB/oct) at 155 Hz, and the LXmini high-pass at LR36-130 Hz. The extra overlap along with phase shifts from the differing slopes improved the wide, deep notches in the frequency response. Definition of bass and low guitar notes and low male vocals went from mushy and unclear to well-defined and natural sounding, LF response in general filled in and seemed smoother and more properly represented, although not perfect, and SS&I remained precise and cohesive with no shifting as the crossover values were moved lower in frequency.
Often, an easy way to quicken bass that seems sluggish is to add some mass to the speaker enclosure. The ES150P bass delivery was not as tight and quick as it might have been, so a large tile under each unit, with its downward-firing port, seemed a possible way to make them perform in a snappier fashion. Adding bricks using squares of poster putty to increase mass can also work wonders. Neither measure made any difference with the ES150P. The resonating room modes were clearly to blame.
I had recently purchased a package of insulation for treating the front of my room, which patiently awaited that project's arrival at the top of my priority list. Using temporary measures to prop and hold it in place - it is made from recycled from denim and is not an irritant - I covered the front wall with it. The modes, which contained enough energy to ring a bit and make the ES150P seem slow, now die quickly and the bass is as snappy as I have heard it in this room.
I have left out numerous other experiments and changes that affected the LXmini side of the pairing for the better, to be reported on elsewhere. All in all, the pairing of the LXmini with the JBL ES150P subwoofer was a success and I am delighted with the result. Final frequency response was adjusted only with the crossover band levels, no other DSP changes were made from Linkwitz Lab's DSP program values.
Final volume leveling of the ES150P relative to the LXmini was done with Periodic Pink Noise from Room EQ Wizard, 2 octaves to the subs (30 to 120 Hz) vs. 2 octaves to the LXmini (500 to 2 kHz).
From measured flat response in my room - which required changing those crossover levels a little from initial recommended values - I ended up boosting the subwoofer output to +3 dB and the LF driver output to the LXmini to +1 dB. This gave bass that is full and deep while sounding completely natural to my ear, not over-emphasized at all.
Primus - Frizzle Fry
I can crank these tracks as desired. The LXmini is running with an Axiom ADA-1250 4-channel digital amplifier rated at 225 W rms per channel into 8 ohms, which could easily turn all four of the LXmini drivers into burnt cinders at the twist of a knob. I manage the volume with care. Herb's kick drums are not particularly deep or loud in the mix, but are solid and quick, and give a nice punch in the chest. Les Claypool's prominent bass is right where it belongs in the soundstage. As Harold of the Rocks comes to a close with solo percussion runs, all is perfectly placed in the mix and soundstage. A cohesive and natural soundstage at all frequencies, with all percussion and bass right where it belongs in the mix, was an inviolate goal of the project, and it has been achieved. At no point does the ear indicate that the drums or bass are coming from the wrong direction or are out of place.
Queens of the Stone Age - Songs for the Deaf
You just have to play this album loud, it is not an option. The LXmini do their part with honors, while the ES150P provide a solid bottom end. The bass frequencies are not particularly challenging through this album, but like to be felt. On No One Knows, they are more prominent, and again sound and feel like they are right where they belong.
Cincinatti Pops - Intro to 'Also Sprach Zarathustra' from 2001 & 2010; Star Trek - Main Theme
This is a fun sequence that we have used during speaker evaluations to see how well towers could handle the booming bass at the beginning of the Star Trek theme. Some drivers simply bottom out. The right volume is where the orchestra feels live, like you are at a concert hall. I did not hold back. Even during the buildup, the low rumble was a little nerve wracking, but the ES150P showed no amount of strain in kicking out those low booms.
Melody Gardot - Baby I'm A Fool
Melody's voice can be particularly difficult for some speakers to image properly on this track. The standup bass and the low knocks on the acoustic guitar toward the track's end can also be revealing. Nothing was improperly placed by ES150P/LXmini setup and tuning.
Tower Of Power - Fanfare, You Know It
The plucky bass guitar on this track is another good bass guitar SS&I test which was passed by the ES150P.
B-52's - Good Stuff, Revolution Earth
The driving kick drum and walking bass make these favorite test tracks. When properly imaged, the kick drum all seems to come from the center of the soundstage, even though the lowest frequencies obviously are too low to localize in that way. That is the way they appear with the ES150P.
Yello - Kiss in Blue
This track is an SS&I workout for any speaker, with deep, strong bass. No challenges here.
Nils Petter Molver - Khmer
Strong, deep off-center percussion is featured on this track, another kind of SS&I workout, and again, imaging perfection, even with the volume WAY up.
Gorillaz, with Lou Reed - Some Kind Of Nature
Radiohead - Airbag, Paranoid Android, Subterranean Homesick Alien.
Looking for tracks with stronger, more challenging bass. But at no point does the system say "subwoofer at work." It is more likely to be accused of having a full-range center channel at work. Not so.
I chose to focus on the two-channel integration of a stereo pair of ES150P subwoofers for this review, specifically running the crossover at higher frequencies than one would normally do in a home cinema system. I was very happy with the results. I would not hesitate to recommend the JBL ES150P for this kind of duty.